Magnetic measuring methods are usually used nowadays in the field of torque sensors and rotation angle sensors. One example of such is the TSS-1 torque sensor from Robert Bosch GmbH, in which a magnetic field which changes during a rotary motion is detected using Hall sensors, and a measured signal is converted into a rotation angle signal or a torque signal. These sensors are characterized in particular by their high angular resolution, which may sometimes be less than 0.01°.
However, for these types of sensors, high manufacturing costs result for large, high-volume mass applications due to complicated and expensive components, for example an oppositely polarized magnet ring or the metallic flux conducting elements necessary for conducting the magnetic flux. In addition, the complicated assembly and connection technology must be taken into account, since the measuring Hall elements are aligned with very high positional accuracy with respect to the magnetic flux, and this position must be maintained over the entire service life of a sensor in order to avoid drift of the sensor.
A sensor system for detecting a differential angle is described in German Patent Application No. DE 10 2005 031 086 A1. This sensor system includes at least one magnetic field-sensitive sensor element, with the aid of which the magnetic field information of a magnetic circuit composed of a magnetic pole wheel and ferromagnetic flux rings having teeth is evaluatable. The teeth extend in the radial direction for radially tapping the magnetic field information of the magnetic pole wheel.
A capacitive angular position sensor is described in European Patent No. EP 1 396 703 A2. This sensor includes two circular capacitive plates and a semicircular rotor, made of dielectric material, which is situated on a shaft to be rotatable with the shaft. The two plates are stationarily mounted on the shaft. Thus, a capacitance between the two plates is defined by an angle-dependent position of the dielectric rotor, via which an angle of the shaft may in turn be determined.
A system for determining a speed and an angular position of a shaft is described in U.S. Pat. No. 3,421,371. The speed and angular position of the shaft are likewise capacitively detected. For this purpose, the system likewise includes two plates of a capacitor which are situated fixed in place on the shaft, and a dielectric rotor, rotatably attached to the shaft, which is situated between these two plates. It is provided that the rotor is designed as a circular disk, this rotor being attached to the shaft at a point which is offset with respect to the center point of the rotor.
PCT Application No. WO 98/43046 A2 describes a capacitive sensor for rotation angle and angular velocity, having two electrodes in the shape of annular sectors which are insulated from one another and which have predefined centering angles. Between these two electrodes, a rotor having at least one sector-shaped blade which is aligned with respect to the rotational axis of the shaft is situated on a shaft.
A torque sensor is described in Japanese Patent Application No. JP 61076928 A, which includes a first rotation angle sensor and a second rotation angle sensor which are connected to one another via a torsion bar.